Advanced malignant diseases such as castration-resistant prostate cancer (CRPC) are difficult to manage because these cancers tend to metastasize and are often poorly responsive to the standard chemotherapy. RNA-interference (RNAi) therapeutics, e.g. small-interfering RNAs (siRNAs), hold high potential for silencing critical molecular pathways to restore the cancer chemosensitivity and slow down the spread of cancer. Our group has recently developed a new generation of hybrid nanotechnology, represented by lipid-polymer hybrid nanocarrier (LPN), to provide sustained, controlled intracellular siRNA supply efficiently at low normal tissue toxicity. Using LPN for anti-survivin-siRNA delivery, we reported significant RNAi-chemosensitization in vitro and in vivo for extended time. Our results further demonstrated that by silencing survivin, we were able to substantially suppress the metastatic potential of CRPC. LPN-integrated RNAi-therapy therefore may simultaneously tackle the two most devastating problems of advanced CRPC. In this application, this promising therapy will be implemented using a cancer-surface targeting LPN. Specifically, we will (1) evaluate the in vivo tumor-targeting capabilities and pharmacokinetic properties of LPN in an orthotopic model of metastatic CRPC; (2) study the pharmacodynamic and therapeutic properties of LPN carrying anti-survivin siRNA for optimal CRPC chemosensitization and control of metastasis; (3) evaluate the therapeutic outcomes of chemo-RNAi combination therapy consisting of docetaxel and LPN carrying anti-survivin siRNA for CRPC treatment. Relevance to Public Health. Successful completion of this project will validate and optimize a nanotechnology-integrated RNAi-therapy for preventing advanced-stage cancers from spreading to the healthy tissues, and turning these often non-responsive cancers responsive to the standard drug treatment again.